The fierce and very public feud between Elon Musk and the rapper Azealia Banks was reignited on Friday after the tech billionaire’s lawyers attacked the rapper’s credibility in a filing in a shareholder lawsuit.

“They are still slighting me like I don’t have plenty more dirt to spill on Elon,” Banks wrote on Instagram on Friday. “This is going to get extremely ugly … Elon will learn very soon who is more powerful of us two.”

She has since deleted the post.

The revived feud between Banks and Musk is just the latest fallout from the Tesla CEO’s infamous announcement on Twitter that he had secured funding to take Tesla private at $420 per share.

Banks had posted extensively about her time in Musk’s home on Instagram, alleging that she had been invited by Musk’s then girlfriend Claire Boucher, better know as Grimes, for a recording session, only to end up waiting around the house while the musician comforted her boyfriend for “being too stupid not to go on Twitter while on acid”.

According to Musk’s attorney’s filing on Friday, which was first reported by Bloomberg, the plaintiffs have sought subpoenas for Grimes, Banks, and three media outlets (the New York Times, Gizmodo and Business Insider) that interviewed either Banks or Musk about their dispute.

“It is evident that this is really more of an effort to sensationalize these proceedings than a legitimate attempt to preserve evidence,” Musk’s attorney Dean Kristy wrote in the filing.

Elon Musk and Grimes at the Met Gala in 2018. Photograph: Stephen Lovekin/Variety/Rex/Shutterstock

In the filing, Kristy refers to media reports describing Banks’ “history of making bold and sometimes unverified claims” to question her credibility as a witness. The filing also cites an article, in which a reporter characterized Banks calling Musk a caveman as “vaguely eugenicist”, as further evidence of her untrustworthiness.

Kristy also invoked a tale resurfaced recently by Vanity Fair that Jack Dorsey, the Twitter CEO, once sent Banks hair clippings to make him a protective amulet.

“This is simply not the type of witness, or factual record, that could justify the required finding of exceptional circumstances necessary” to allow the subpoenas, the filing argues.

Banks appears to have taken exception to Kristy’s filing, an excerpt of which she posted as a screenshot in her now-deleted Instagram post.

“I’m now even more angered by the fact that his lawyer is falsely stating I lied after being vindicated in both incidents with Russell Crowe and Jack Dorsey,” she wrote.